This invention relates to an apparatus for reading magnetic character waveforms, like E13B, which are imprinted on documents, like checks, even though there is a variation in the speed of the document as it is moved through the apparatus.
In some prior art MICR (Magnetic Ink Character Recognition) readers, it is common to use an expensive, constant velocity motor to move the document at a constant velocity past the associated read head within the apparatus. With a constant speed, the anticipated positive magnetic peaks, negative peaks, and lack of peaks appear within the designated "windows" for the character being read, providing an accurate reading of the character. When the speed of the document changes for various reasons, the magnetic peaks read may not fall within the anticipated windows or time slots, causing the character to be rejected.
Another prior art technique of adjusting to variations in the speed of the document as it passes the associated read head is to adjust the width of the examining "window" to enable an anticipated magnetic peak to fall within the anticipated window.